Thread: ND filters - colour cast

Good morning, I am not certain that I have the answers you are looking for as I have only just ordered a 12 stop ND filter to try the same technique. But at this point I have more question of you and hopefully the answers will come.

1. Are you exporting your images from the camera as RAW or Jpeg images?
2. What image processing editing software are you using? You mention Photoshop and Bridge, What versions are they and do you have any add-ons which you use?
3. What settings did you use on the camera;
a. Auto exposure or manual exposure?
b. Auto focus or manual focus?
i. Single servo or continuous servo?
ii. Single point or multi point focus?
c. What was the exposure mode: manual, aperture priority, shutter priority, auto?
d. ISO: Auto or manual setting. Looks like it was 100 ISO, but did you set it or was it set automatically by the camera?
e. What was the white balance setting?
f. Where any options, such as long exposure noise reduction, switched on?
4. From the exposure settings you gave in your post it looks like it was a bright sunny day when the images were taken, am I correct?
5. Is the colour of the rocks in the second image ( non-ND) accurate? I have never been to Terrigal, so don't have any reference, but the image looks a bit yellow to me compared with what I am used to.
6. What editing adjustments did you make to the first image?
7. Are the Cokin filters solid or gellatine and how old are they?

One observation at this point. From my reading of the subject, I will be using significantly longer exposures to get the classic fine art 'silky' motion that I am aiming for. Something of the order of 30 seconds to 3 minutes. Hence the reason for ordering a 12 stop ND filter. Even with this filter, I would probably have to shoot in the evening. I think that most of the fine art images in this style that I can recall seeing were predominately in Black & White. I will follow up on the infra red, etc which you mentioned.

Looking forward to your response and working with you to see if we can overcome your problem.

Bob

Have you read this review? ND Filter Color Cast: - Bulbexposures.com - Bulb Exposures - The Blog about Long Exposure Photography!.

The answer may be as simple as changing the ND filter to a different brand. I am off shortly to see if I can change my order if the the Hoya filter which I suspect he will supply does not include the IR inhibitor.

Bob

Beauty a thousand and one questions

Originally Posted by Oldgreybeard

Good morning, I am not certain that I have the answers you are looking for as I have only just ordered a 12 stop ND filter to try the same technique. But at this point I have more question of you and hopefully the answers will come. and a good morning to you

1. Are you exporting your images from the camera as RAW or Jpeg images? both
2. What image processing editing software are you using? You mention Photoshop and Bridge, What versions are they and do you have any add-ons which you use? Photoshop CS5. Bridge is a part of photoshop
3. What settings did you use on the camera;
a. Auto exposure or manual exposure? Manual
b. Auto focus or manual focus? Auto as my eyes aren't what they used to be
i. Single servo or continuous servo? single
ii. Single point or multi point focus? single
c. What was the exposure mode: manual, aperture priority, shutter priority, auto? manual. the second photo may have been aperture priority
d. ISO: Auto or manual setting. Looks like it was 100 ISO, but did you set it or was it set automatically by the camera? 100 ISO set by me. I've just realised the second photo was 200 ISO
e. What was the white balance setting? auto
f. Where any options, such as long exposure noise reduction, switched on? no
4. From the exposure settings you gave in your post it looks like it was a bright sunny day when the images were taken, am I correct? yep very bright and mid to late morning - I'll comment on this aspect later
5. Is the colour of the rocks in the second image ( non-ND) accurate? I have never been to Terrigal, so don't have any reference, but the image looks a bit yellow to me compared with what I am used to. Reasonably accurate I think
6. What editing adjustments did you make to the first image? nil
7. Are the Cokin filters solid or gellatine and how old are they? solid glass and about 3 months old - Father's Day/Birthday pressies

One observation at this point. From my reading of the subject, I will be using significantly longer exposures to get the classic fine art 'silky' motion that I am aiming for. Something of the order of 30 seconds to 3 minutes. Hence the reason for ordering a 12 stop ND filter. Even with this filter, I would probably have to shoot in the evening. I think that most of the fine art images in this style that I can recall seeing were predominately in Black & White. I will follow up on the infra red, etc which you mentioned.

Looking forward to your response and working with you to see if we can overcome your problem. I've a few thoughts which I'll post in another post

Bob

Originally Posted by Oldgreybeard

Have you read this review? ND Filter ColorCast: - Bulbexposures.com - Bulb Exposures - The Blog about Long Exposure Photography!.

The answer may be as simple as changing the ND filter to a different brand. I am off shortly to see if I can change my order if the the Hoya filter which I suspect he will supply does not include the IR inhibitor.

Bob

Thanks
From what I've been reading and seeing most, if not all, have some colour cast. Those that don't are in the hundreds of dollars each

Interesting tutorial on the site linked to by oldgreybeard

Long Exposure Tutorial - Bulb Exposures - The Blog about Long Exposure Photography!

Having just bought a variable ND filter (77mm) I will start to play around with it and will get a step up ring for my smaller filter size lenses.

Originally Posted by Sawdust Maker

Thanks
From what I've been reading and seeing most, if not all, have some colour cast. Those that don't are in the hundreds of dollars each

The price through B & H (USA) shipped to Australia for 7 stop IR ND filter is US$100.

I don't know if Cokin have a IR filter, but would it be a possibility to stack an IR filter with the ND filter?

Incidentally, your settings are the same as I would have used - so we are either both right or both wrong!A[pologies for all the questions, just a bad habit from years of teaching photography and trying to solve student's problems.

Bob

Fred - Think Ive read that sometime in the past

Bob - I was sort of looking at Singh-Ray or the Formatt-Hitech or the Lee
note I said looking not necessarily buying - still a lot of looking and researching yet

here's a bloke commenting on why he moved from one make to another

Just found this item. It suggests the IR problem is attributed to cropped sensors (FX format digital cameras). It will be interesting to see if I have the same problem on my full frame D800.

Photovideo.com.au have the 77mm 10 stop filter for $149.00. (See thier description below)

The Tiffen IR ND 3.0 is a Neutral Density filter providing 10-stop exposure absorption. The high density blocks light emission of the visual spectrum into the camera, allowing you to photograph with a much slower shutter speed or at a wider aperture than required. This gives the photographer two techniques; the filter is ideal then for long exposures in which anything with movement in the image is desired to appear blurred. The second is in which the photographer needs to use faster or more wide open lens apertures to create less depth of field.
The IR blocker allows for less Infra-Red pollution which has been attributed to long exposures on smaller crop sensors.

In Bob's 1001 questions I commented that I would get back on the sunlight aspect

the photos in my first post were taken in bright sunlight - looking at the metadata at about 9:10 am last Thursday
for ease I've attached them again

test no ND_2934.jpg Test ND no process_2930.jpg

I also took some photos the day before where it was quite overcast (as can be seen from the sea colour)

CC 1 nf_2687.jpg CC 2 filters_2693.jpg

1st photo is without filters same lens, ISO 200 f32 1/6 (also says I over exposed by .33)
2nd photo with filters, ISO 100 f32 2s
interestingly these photos were taken at about 9:30am (on 13 Jan) a bit further around the headland

It is interesting that there is a lot less colour cast in this series than the other. These are JPEG images as for some unknown reason I didn't think to set up for RAW

Unfortunately I'm home now and cannot wander out and do some more controlled shots

this is the second image post processed in photoshop


CC 3 filters corrected_2693.jpg

I'll do another post shortly on the post processing methods I've found so far

Originally Posted by Oldgreybeard

Just found this item. It suggests the IR problem is attributed to cropped sensors (FX format digital cameras). It will be interesting to see if I have the same problem on my full frame D800.

Photovideo.com.au have the 77mm 10 stop filter for $149.00. (See thier description below)

The Tiffen IR ND 3.0 is a Neutral Density filter providing 10-stop exposure absorption. The high density blocks light emission of the visual spectrum into the camera, allowing you to photograph with a much slower shutter speed or at a wider aperture than required. This gives the photographer two techniques; the filter is ideal then for long exposures in which anything with movement in the image is desired to appear blurred. The second is in which the photographer needs to use faster or more wide open lens apertures to create less depth of field.
The IR blocker allows for less Infra-Red pollution which has been attributed to long exposures on smaller crop sensors.

Another reason to wander out and get an EOS 1DX
How many brownie points do you think I'd need?

Originally Posted by Oldgreybeard

The price through B & H (USA) shipped to Australia for 7 stop IR ND filter is US$100.

I don't know if Cokin have a IR filter, but would it be a possibility to stack an IR filter with the ND filter?

Incidentally, your settings are the same as I would have used - so we are either both right or both wrong!A[pologies for all the questions, just a bad habit from years of teaching photography and trying to solve student's problems.

Bob

Interesting question, one I pondered for a few moments. I have used an infrared filter quite extensively with film, especially with Kodak High Speed Infrared film. All infrared filters I have used, including my own which is a Hoya Infrared (R72), are visually opaque.

This means one cannot normally see through them, although you can, within reason, detect where infrared is strongest or its presence by quickly viewing directly through the filter when held up to your eye with all (or most) other light blocked by your hand/fingers.

If you were using ND filter(s) and determined where your subject was and presumably using a tripod, then you could compose first, then pop the R72 filter before or after any ND filtration.

One possible way to prove or disprove this visually in one exposure, would be to use a centre graduated filter, the type normally used with very wide lenses to correct for edge fall off, with and without an R72 filter.

I have a Heliopan centre graduated filter that is 67mm, but my R72 filter is 52mm, so I cannot check this myself with someone else's electronic camera; I only use film for photography.

Mick.

I borrowed a friend's set of Cokin filters to try out a few years ago, and found that stacking 2 or more filters led to a much worse colour cast (totally horrible purple) than just a single one (which also had some magenta cast). Playing with White Balance afterwards improved it reasonably well.

Interesting question, one I pondered for a few moments. I have used an infrared filter quite extensively with film, especially with Kodak High Speed Infrared film. All infrared filters I have used, including my own which is a Hoya Infrared (R72), are visually opaque.

I suspect that this would be the reverse of what we want - that is we want to block IR whereas the filter used with the IR film, from memory, allowed IR and block visual frequencies.

Anyway the third photo is the 1st after a bit of a play with the white balance in Photoshop.

Rather than trying to correct the colour cast by adjusting the white balance control, have you tried using Curves adjustment using the individual colour channels? That would be my preferred method.

Slightly off the main topic, but I have just been talking with the manager of my local photo gear supplier about this subject; particularly about effects of using ND filters on cropped sensors V Full frame as well as the effects of stacking ND filters V single higher value filter. To cut a long story short, he is meeting with their wholesale supplier on Wednesday as is going to sound him out on the idea of 'loaning' us a number of ND and variable ND filters for testing. If they are agreeable I will carry out a series of tests comparing different brands, effect of single v stacked and variable NB filters. I will also compare the results of some tests on cropped sensor v full frame cameras.The results will be written up as a formal review for the use of the wholesaler, retailer and myself. Whether it goes ahead will depend on the wholesaler. Will let everyone know if the project goes ahead.

Bob

Interesting - hope it goes ahead and I'd love to see the results

I wonder whether the demarcation line is actually between cropped sensor and full frame?
Could it be, say, between professional and pro-sumer cameras
ie I wonder whether the Canon 5D and/or 6D has the same issue - I've read somewhere that the 1D doesn't

PS curves is one or two of the methods I'll discuss shortly